Vibration suppression analysis and experimental test of additional constrained damping layer in space science experiment cabinet

Aiming at the problem that the vibration of the space science experimental cabinet is too large during the launch phase of the rocket, the viscoelastic constrained damping layer is used to suppress the vibration. Firstly, to explore the vibration suppression mechanism of the constrained damping layer, the dynamic model of the constrained damping layer is established and the modal loss factor is calculated. Secondly, the influence of the modulus, material thickness, and the position and the area of the damping layer on the loss factor of the structure is analyzed. Finally, the simulation and experiment methods are used to calculate and verify the space science experiment cabinet with additional constrained damping layer. The results show that the viscoelastic constrained damping can effectively reduce the vibration level of the space science experiment cabinet, and the acceleration response in the resonance region is reduced by more than 56%. The viscoelastic constrained damping structure is simple and easy to realize, which can suppress the vibration of the space payload design is of great significance.

Topology optimization of partial constrained layer damping treatment on plate for maximizing modal loss factors

Constrained layer damping treatment is widely used to suppress the vibration and noise of thin-walled structures. However, full coverage of constrained damping layer will increase unnecessary additional mass, resulting in material waste and cannot effectively improve the damping performance of the composite structure. In this article, a topology optimization approach is proposed to realize the optimal distribution of constrained damping layer. The design objective is to maximize modal loss factors solved by the modal strain energy method under the constraint of volume. Taking the relative density of the finite element of the constrained damping layer as design variable, the solid isotropic material with penalization method is used to realize the optimal topological distribution of the damping material on the surface of the metal substrate. Then the moving asymptote method is adopted as an optimizer to search the optimal layout of the constrained damping layer. Based on a modified modal superposition method, the sensitivities of the objective function with respect to the design variables are obtained. Numerical examples and experiments are presented for illustrating the validity and efficiency of this approach. The results show that the objective function converges to the optimal value smoothly, and the optimized modal loss factors have been significantly improved. The layouts of the constrained damping layer after optimization are clear and reasonable, and its distributions are affected by both the damping layer and the constraining layer. Each part of the constrained damping layer after optimizing can greatly improve the damping performance of the structure.

Chatter and Stability Analysis of the Slender Composite Boring Bar with Constrained Damping Layer

This study investigates the chattering stability of the composite boring bar with a constrained damping layer during the deep-hole boring process in depth. Based on the Euler-Bernoulli beam theory, the regenerative chattering linear kinetic model of the composite boring bar with a constrained damping layer was established, and the computational formulas of the rotating speed of the spindle and the corresponding limit cutting depth were derived. By analyzing the chattering stability, the cutting stability lobe curves of the composite boring bar with a constrained damping layer were plotted so as to reveal the effects of the materials of both base layer and constrained layer, the ply angle, the damping composite structure (free or constrained damping structure) and the thickness of various layers on the chattering stability of the boring bar. Through the analysis of dynamic stiffness, the chatter stability analysis theory of a composite boring bar with a constrained damping layer is verified.

Stiffness-Damping Matching Modelling for Vibration Isolation System of Roadheader ECB

The electronic control box (ECB) is a key and precise component of a roadheader. The vibration of the ECB is an increasingly prominent issue as the machine capacity grows. In order to promote the isolation effect of the ECB, a whole-body vibration model considering the cutting effect is derived, based upon which the stiffness-damping matching strategy for the ECB isolator is acquired. For engineering application, the tubular constrained damping isolator (TCDI) is developed based on the constrained damping theory and the matching strategy. The theoretical results show that the isolation effect of the ECB isolator strengthens as the stiffness coefficients decline and the damping coefficients increase. The configurations with larger rear stiffness coefficients and larger front damping coefficients could lead to a better vibration control effect. The experiment results indicate that the TCDI exhibits a greater capability of isolating the impact excitation than the traditional E-type isolator, thus verifying the whole-body vibration model for the roadheader and the matching strategy for the ECB isolator. This research can provide theoretical and practical references for the investigation of the dynamic behaviour of complex viscoelastic structures.

On the Region for the Application of Passive Damping Treatment and Loss Factor Enhancement

The loss factor of a structure is significantly improved by using constrained damping treatment. For a mass efficient design, the damping material is to be applied at suitable locations. The studies reported in literature use the modal strain energy distribution in the viscoelastic material or the strain energy distribution in the base structure as tools to arrive at these suitable locations for the damping treatment. It is shown here that the regions identified through the above criteria need not be suitable for certain bending modes of vibration. A new approach is proposed in which the strain in the viscoelastic material and the angle of flexure are shown to be more reliable in arriving at the locations for the damping treatment. Providing damping layers at identified locations using these parameters results in significant loss factors with minimal added mass.

Vibration Characteristic of a Transition Constrained Damping Beam Based on the Shear Dissipating Energy Assumption

Adding a “transition layer” could further improve the dissipation ability of the original constrained damping structure to the external vibration. At the same time, the addition of the transition layer brings many difficulties in establishing the model and acquiring the relevant characteristics of the• structure. Based on the shear dissipating energy assumption and the Hamilton principle, the finite element model of the transition constrained damping beam is established. On the basis of this reasonable assumption, the whole derivation process is simplified and easy to read by regularizing the element stiffness and mass matrix, and the expression of loss factor and natural frequency of damping beam is obtained. In order to verify the correctness of the model, the computed results are compared with the analytical solution, and both are found to be in good agreement. Taking the cantilever damping beam as an example, the influence of the material choice of the transition layer and the structural parameters on the natural frequency and the loss factor of the structure are discussed. The results of this paper would lay a good foundation for further optimization and practical engineering application.

Design analysis and experimental verification of vibration reduction of spatial composite damping truss structure

In order to solve the problem that the photoelectric instrument may fail when the vibration response of the truss composite structure is too large, the method of applying the viscoelastic-constrained damping layer on the truss wall and the box panel is used to reduce the vibration of the whole structure. In this article, a broken long tube with viscoelastic-constrained damping layer is introduced. The long tube of the original structure is broken into two identical short tubes, and a tube with free damping layer is added to the junction of the two short pipes, which is connected by adhesive and broken long pipe. By analyzing the frequency response of the traditional space truss and spaceflight load structure, and a broken long tube structure, the acceleration response cloud diagram and the acceleration response curve of the fixed measuring node are obtained. Experiments were carried out to verify the feasibility of the structure. The test results show that the method of broken long pipe with viscoelastic-constrained damping layer can achieve better damping effect than the traditional truss structure, and it can effectively reduce the vibration level of the space load at the end of the truss, and has important reference significant for the vibration reduction design of other space structures.

Distribution Optimization of Constrained Damping Materials Covering on Typical Panels Under Random Vibration

This paper studies topology optimization of metallic and composite panels of three different configurations (flat, three-bay and 3×3 grid) covered by the constrained damping materials considering first modal loss factors. The vibration experiments seek to obtain the first modal loss factor and first modal frequency for the aforementioned panels, and corresponding finite element (FE) simulations are completed using commercial software ABAQUS R . According to simulation results, the distribution of constrained damping materials is optimized with evolutionary structural optimization (ESO) method developed using MATLAB. The results show that the first modal loss factors of optimized panels are reduced slightly if the constrained damping material is removed by 50%. Under the base excitation near each first modal frequency, the maximum root mean square of Von Mises equivalent stress (RMISES) of optimized flat panels and 3×3 grid stiffened panels decreases compared with panels without constrained damping materials. However, the maximum RMISES value of optimized three-bay stiffened panels nearly remains unchanged due to the configuration type of the stiffeners. These results conclude that the three-bay stiffened panel is the best to reduce the maximum RMISES value of at base structure with the same additional mass